3D printed robot bird can dive, spiral, flip - and fool a hawk

May.17, 2013

For years we have been trying to mimics nature and build our own versions of mechanical wings. But it's been a breakthrough that's been out of reach for engineers — until now.

Hugh Bruck and Satyandra K. Gupta, professor of mechanical engineering at the University of Maryland, have developed a robotic bird called Robo Raven that has a truly clever design. It can dive, spiral, even back flip and its wing motion and silhouette are so realistic that even a hawk has attacked it in flight.

Students Luke Roberts, John Gerdes, and Ariel Perez-Rosado with Robo Raven. Credit: University of Maryland

And how hard could it be to make a robot bird whose wings can flap independently of each other? It took the team eight years and a lot of speed bumps to arrive at this stage.

The Robo Raven can be programmed to perform any desired motion, enabling the bird to perform aerobatic maneuvers. This is the first time a robotic bird with these capabilities has been built and successfully flown.

This new new robot, Robo Raven uses two programmable motors that can be synchronized electronically to coordinate motion between the wings. The challenge was that the two actuators required a bigger battery and an on-board micro controller, which initially made Robo Raven too heavy to fly.

"How did we get Robo Raven to 'diet' and lose weight?" Gupta asks. "We used advanced manufacturing processes such as 3D printing and laser cutting to create lightweight polymer parts."

But smarter manufacturing and lighter parts were only part of the solution.

So the team did three more things to get Robo Raven airborne. They programmed motion profiles that ensured wings maintained optimal velocity while flapping to achieve the right balance between lift and thrust. They developed a way to measure aerodynamic forces generated during the flapping cycle, enabling them to evaluate a range of wing designs and quickly select the best one. Finally, the team performed system-level optimization to make sure all components worked well together and provided peak performance as an integrated system.

"We can now program any desired motion patterns for the wings," Gupta says. "This allows us to try new in-flight aerobatics—like diving and rolling—that would have not been possible before, and brings us a big step closer to faithfully reproducing the way real birds fly."